Imager apparatus are normally used in digital radiography to allow a physician to examine digitally recorded images in a traditional manner by viewing a transparency rather than a computer display. These apparatus can use electronic capabilities to process (by reducing, enlarging, zooming, etc.) and compose several images on the same photographic film. These apparatus are called multi-imagers.
These apparatus normally include a light tight casing which houses an image projector which projects the processed and composed images onto a photographic film resting at an exposure site on a glass plate, called a focal plane. At exposure site, film drivers ensure proper movement of the film. Components are also provided to transfer the film from a feeding magazine to the exposure site and from the exposure site to a receiving magazine.
A critical aspect of the accuracy of image reproduction is in the optical characteristics of the focal plane. A glass plate typically is used at the focal plane to support the film. However, very small imperfections in planarity, surface parallelism, and finishing and positioning and improper cleaning or maintenance of the glass plate can lead to inaccurate image reproduction.
There is a need for an imager apparatus which produces a highly accurate image reproduction, without defects or distortions. This is critical in the medical field since a proper medical interpretation of an image requires an accurate reproduction.